Establishing a well-allocated portfolio can be a tricky process when you're just getting started in investing. Beyond figuring out what asset mix is appropriate for you, the process of implementing your target allocation can itself be a challenge when you have smaller amounts of money at your disposal.

If you haven't yet developed a substantial nest egg, it can be hard to spread your money out to get exposure to a diversified array of asset classes, and many mutual funds have minimums high enough to complicate getting started. Take Vanguard funds, for instance. While the firm is known for being investor-friendly, with some of the lowest fees in the industry, the smallest initial investment for most Vanguard funds is $3,000--which starts to seem intimidating if you're a new investor who wants to diversify between a handful of funds. (Vanguard STAR is one exception--its minimum initial purchase is just $1,000.)

Luckily, there are ways for those with modest investing funds to get allocated.

Employer-Sponsored Plans
If you're just starting out, your 401(k) or other employer-sponsored plan is your best friend. Because investment minimums are typically waived for participants, 401(k)s make it easy to slowly build up money in different investments.

And getting your asset allocation on track is painless within a 401(k)--simply assign the percentage of your contributions directly to each investment you select. Of course, you may need to rebalance your existing holdings over time if your allocation is substantially out of whack.

Target-Date Funds
Target-date funds allow you to get diversification in one shot, through investing in a single mutual fund. You invest in a target-date fund for the date when you expect to retire, and the fund manager handles the nitty-gritty allocation details, changing your holdings as you get closer to retirement so that you have, for example, fewer equity holdings and more bond holdings.

Target-date funds from different companies can vary substantially in the types of holdings they have and their "glide paths," or the allocation course they follow as you approach your retirement date. Look at target-date offerings for your estimated retirement date from several different companies to choose one that suits you. Two of our favorites are the offerings from Vanguard and T. Rowe Price. T. Rowe's target-date funds tend to be a bit more equity-heavy. Read Morningstar's analysis of target-date fund series here.

The downside to this option is that you give up full control of your investments--you are essentially handing over the reins of your portfolio to your target-date manager.

Low-Minimum Funds
If you're more of a do-it-yourself investor, the most straightforward option--simply scouting out funds with low minimums--can also work. Using Morningstar's Premium Fund Screener, you can identify funds with minimums lower than $1,000, $500, or even $100. Several funds offer lower minimums for IRA participants and for investors who sign up for Automatic Investment Plans, or AIPs. You'll probably be making lots of small additional purchases, so you should also look at funds' additional purchase minimums and focus on no-load funds. In addition to using the screener, you can find minimum purchase information for regular investments, IRAs, and AIPs under the Purchase tab on each Morningstar.com fund report.

Using the Premium screener, we filtered down our Analyst Pick list to those accessible with only $500, either outright or through an IRA or AIP. Fifty-five funds passed the screen as of Oct. 17--a pretty sizable group to choose from, though some will be more specialized than you'd need for the core of your portfolio. Click here to run the screen yourself.

Reducing the minimum purchase to $250 (including the IRA and AIP avenues) still leaves 40 funds.